Typically, walls have been flamed using the so-called stick flaming method. In the stick frame method walls are manufactured from studs and bottom and top framing members called plates. The studs are typically made from lumber and are usually made out of nominal two inch thickness lumber. Typically, the studs and plates may be made from lumber referred to as a two-by-four. A two-by-four is a piece of lumber of desired length having nominal dimensions of two inch thickness by four inch width. Stick flaming typically involves the technique of nailing the studs to the top and bottom plates. The convention has developed that the studs are placed along the plate spaced 16" on centers.
The wall manufactured from two-by-four building materials is relatively strong. That wall will normally support most of the structural loads which may be imposed in residential construction and often will be strong enough to support the loads required in industrial and commercial buildings as well. However, where the studs are used on outside walls and where a need for extra insulation occurs, then the width of the studs may be increased to nominal 6" boards, or in extreme cases, to nominal 8" boards. The extra width provides the necessary space to increase the insulation that is packed into the walls between the studs.
When the walls are used in the internal walls of the building and have no need for insulation then width of the material may be varied depending upon whether the wall is a structural wall, that is to say, supporting a load, or whether the wall is merely a divider wall to divide up the enclosed spaces. For ease of construction, typically most interior walls have also been manufactured from two-by-four nominally dimensioned lumber.
Construction lumber is becoming more and more scarce and accordingly is becoming more and more expensive. Additionally, working with lumber involves certain difficulties. Unless the lumber is properly dried then the two-by studs will warp or twist over time as the studs dry in the building. This can often cause changes to the wall which in turn will lead to cracking of the materials used to cover the wall which typically may be wall board and the like. As construction lumber has become more and more expensive, alternatives have been developed to the use of wooden structural members.
One of the alternatives that has developed is the use of steel studs. Steel studs can be made in roll forming machines from strips of steel of convenient gauge or thickness. The roll forming machine can roll the strip steel into a stud of any configuration. When steel studs are used, typically they are used together with upper and lower tracks into which the steel studs are intended to be placed.
Steel studs have several advantages over wooden studs. Steel studs are lighter than wooden studs for equal strength. Steel studs, of course, have no tendency to warp and thus a wall when manufactured from steel studs will not be subject to warping as the material dries and thus provides a more secure surface against which the wall surfacing materials may be affixed. Although steel studs are now well-known, there have been certain difficulties in working with steel studs.
One of the difficulties is the positioning of the stud in the upper and lower track. Another is the proper fixation of the stud into the track. Because of the convention which has become accepted for spacing for wooden studs, steel studs are similarly placed 16" on centres. This is not so much a strength requirement as it is a convention requirement so that the steel studs can be used without difficult with common building materials such as wall board which typically comes in sheet form of four foot width. The four foot width allows the sheet to be affixed to the studs at either edge and at two strips equally spaced from the edges. Where however the facing material is sufficiently strong, the studs may be placed further apart such as 24" on centres which still facilities use with four foot wide sheet facing materials while providing adequate strength. Generally stud spacing such as 16 or 24" on centres is dictated by applicable building codes.
Because steel studs are manufactured in a roll forming machine the steel studs can be made to any configuration or any dimension as desired by the building designer. Accordingly, if steel studs are to be used in an exterior wall where significant levels of insulation are required, then the studs may be manufactured of sufficient width to approximate the same dimension as a two-by-six wooden stud or even a two-by-eight wooden stud where super insulation is required.
With the known construction using two-by-four studs the process for manufacturing a wall from such building materials requires the use of skilled framing carpenters. The framing carpenters have the job of cutting the studs to the correct length. The correct length is determined by the height of the wall which typically may be of the order of 8 feet but may also be higher particularly in commercial and industrial buildings. When a number of studs have been cut to length, the carpenter must then lay out the location of where the studs will be attached to the upper and lower plates. The lay out of the studs involves the considerations of the strength of the wall as well as the other features of the wall. Where there are no other features of the wall the studs will be placed according to convention spaced 16" on centres. Where, however, the wall contains doors, windows, other openings or requires structure to facilitate the joining of intersections of meeting walls then studs must be placed where required. Typically when a window is framed a basic 16" on centre spacing will be maintained but various shorter studs some times referred to as cripple studs or other studs some times referred to as jack studs must be placed to ensure that the location of the window or door does not effect the overall strength of the wall. Even where the wall is an interior non-load bearing wall the studs must still be placed to ensure integrity of the wall when accommodating interior doors, intersecting walls and the like. All of this requires that the framing carpenter be capable of reading the architectural or structural plans for the wall and then laying out the stud spacing on the top and bottom plates. The framing carpenter then nails the studs to the plates and must ensure that the wall so manufactured is square and of the correct height and length.
The time to prepare and install the structural flaming in a house whether residential, commercial or industrial is a significant portion of the building time and is a significant cost factor in terms of both time and materials.
With the use of steel studs the same basic requirements must be met. The upper and lower tracks or channels must be laid out and the framer must now have reference to the plans and lay out the location of the studs on the top and bottom channels. When steel studs are fixed in their location in channels, most often screws are used. The screws will pass through the flange of the stud and the flange of the track. Typically the channels are laid out on a floor and studs positioned as required. As each stud is correctly positioned, a screw is driven through the channel and through one flange of the stud. A second screw in each stud cannot be installed as the wall is on the floor. When all studs are fastened with one screw, the wall can be flipped over and the second screw installed to complete each stud-channel connection. Often, in practice, the second screws are not applied if applied at all, until the wall has been positioned upright in place. This then requires the framer to climb up and down ladders to complete both top and bottom connections.
Another of the problems that has occurred in the use of metal studs and metal tracks is the problem of fully seating the stud in the track. If the track is not properly shaped then the stud may not be fully seated in the track. This is something that may not be immediately apparent to the framer. When the framer attaches a stud in place that is not fully seated in the track, the framer may not be aware of the fact that the misseating error has occurred. This unfortunately means that when a load is applied to the wall then the screw or screws fixing the stud location become structural members and in fact support the load carried on the stud. Where a metal frame wall is intended to be load bearing, the intention is that the load be communicated directly from the upper track to the stud and then to the lower track. If the stud is not properly seated in for example the upper track, then the load passes from the upper track to the screw, from the screw to the stud and creates a point of possible failure. Because of this problem, steel studs have most commonly been used in non-load bearing walls even though steel studs are stronger than wooden studs.
Typically today framing of wooden studs and headers can be done by means of a pneumatic driven nail gun. This has speeded up the nailing component of the time involved. Similarly, the installation of screws in steel studs is most often done by a powered screw gun which may be either air or electrically driven. There is however still considerable time involved in the layout and installation of the fasteners which locate the studs in the track.